Method for casting stereotype plates



Feb. 229 i938. W, BUNGAQ 2,109,207

METHOD FOR CASTING STEREOTYPE PLATES Filed Sept. 26, 1934 lO Sheets-Sheet 2 ATTORNEY /wyq N Feb. 22, 1938. G. w. BUNGAY METHOD FOR CASTING STEREOTYPE PLATES l Filed sept. 2e, 1954 1o sheets-sheet 5 IHN ATTORNEY FCB. 22, 1933. Q W UIBUNGAY y H0920? METHOD FOR CASTING STEREOTYPE PLATES Filed Se'pt. 26, 1934 K 10 Shees-SheffI 4 NVENTOR ATTORNEY Feb. 22, 193s.

G. w. EaUNcaAYr 2,109,207

METHOD FOR CASTING STEREOTYE PLATES l Filed Sept. 26, 1934 10 Sheets-Sheet 5 ATTORNEY Feb. 22, 1938. G. w. BUNGAY METHOD FOR CASTING STEREOTYPE PLATES Filbd sept. 26, 1954 1o sheets-Sheet 6 1.a ff 2 i w A yan1-on v Feb. 22, 193s.

G. W. BUNGAY METHOD FOR CASTING STEREOTYPE PLATES vFiled sept. 26, 1954 1o sheets-sheet? M ATTORNEY Feb. 22, 1938. G. w. BUNGAY METHOD FOR CASTING STEREOTYPE PLATES 1o sheets-sheet 8 Filed Sept. 26, 1954 67 ffm W mvENToR EN 7 ATI'ORNEY Feb. 22, 1938. G. w, BUNGAY METHOD FOR CASTING STEREOTYPE PLATES Filed Sept. 26, 1954 10 Sheets-Sheet 9 for' /f Nvsyn ATTORNEY Feb; 22, 1938. G. w. BUNGAY l METHOD FOR CASTING STEREOTYPE PLATES Filed Sept. 2G, 1934 10 Sheets-Sheet' l0 gs: i

ATTORNEY Patented Feb. 22, 1938 UNITED STATES PATENT oFFicE METHOD FOR CASTING STEREOTYPE PLATES Application September 26, 1934, Serial No. 745,550

Claims.

This invention relates to the casting of stereotype plates, and more particularly to a method and apparatus for casting stereotype plates suitable for high quality printing.

Stereotype plates have heretofore been generally considered unsuitable for high quality printing for various reasons well known in the printing art. For example, the printing surface may be irregular due to imperfections in the matrix, uneven cooling of the metal, shrinkage of the metal away from the matrix, bulging of the matrix due to expansion, poorly controlled temperatures, etc. Different plates may be of nonuniform size because of unequal expansion of the matrix, non-uniform shrinkage of the metal, differences in casting temperatures, differences in rates of cooling, and, in general, because of the diiculty in casting two .plates under exactly the same conditions. For these reasons stereotype plates do not possess the denition or registration required for half-tone color printing and quality magazine Work, circulars, and the like, and recourse has been had to electrotype plates for this type of printing, although electrotype plates are expensive, require considerable time to produce, and are generally unsuited for work requiring cheapness and speed.

It is accordinglyan object of this invention to 30 render stereotype plates suitable for high quality printing.

Another object is to improve stereotype plates so that they may compete with electrotype plates as to quality of printing.

35 Another object is to increase the usefulness and availability of stereotype plates.

Another object is to provide a method of casting stereotype plates having uniform printing surfaces, improved denition and registration,

40 greater depth of printing faces, and in general having characteristics suitable for high quality printing.

Another object is to provide a simple, convenient, efficient and dependable apparatus for 45 accomplishing the above purposes.

Another object is to provide a stereotype casting machine of the above type which is convenient and simple to operate.

The invention also consists in the various new 50 and original features of construction and combinations of parts hereinafter set forth and claimed.

A feature of the invention consists in casting the sterotype plate under a pressure adapted to 55 cause the molten metal to penetrate the various impressions in the matrix and in maintaining the metal in pressure engagement with the matrix While the metal cools to the temperature at which it is removed from the casting machine.

In one embodiment, this is accomplished by applying mechanical pressure to the molten metal, accompanied by an impact, sufficient to compress the metal and to cause the metal to penetrate the impressions in the matrix. 'Ihe edges of the matrix are firmly clamped in posi- 10 tion, and, as the metal cools and becomes solidifled, fluid pressure is applied to the back surface thereof to hold the printing face firmly against the matrix and to exert suicient pressure on the matrix to prevent the same from bulging or l5 otherwise distorting due, for example, to expansion caused by the heat of the molten metal. Hence, the stereotype plate is caused to accurately reproduce the original printing form both as to size and registration, a feature particularly im- 20 portant, for example, in half-tone color printing Where accurate registration of the half-tone dots is essential.

The present invention also provides a simplified means for casting a stereotype plate With a 25 finished printing face. This is accomplished by forming the matrix so that the impressions therein are held in correct position in the casting box to reproduce the original printing form in the cast plate and in casting under suiicient pressure to insure penetration of the matrix impressions by the molten metal.

Another feature of the invention consists in the provision of means for maintaining the casting machine at a predetermined temperature during the casting operations. The casting is preferably removed from the machine at an elevated temperature and the cooling is completed under conditions which prevent warping thereof.

Another feature consists in maintaining transverse pressure on the back of the cast plate to compensate for shrinkage and to maintain the plate in pressure engagement with the matrix While cooling.

Another feature consists in casting the stereotype plates under controlled conditions so that the various plates are uniform 'as to size, definition, registration, etc.

Various other features and advantages will be apparent as the nature of the invention is more fully disclosed.

Although the various novel features which are believed to be characteristic of this invention will be pointed out in the claims appended thereto, the invention itself, as to lits objects and ad- 55 Figure 2 is a front elevation of the machine illustrated in Figure 1.

Figure 3 is a rear elevation thereof. Figure 4 is a top plan view thereof.

Figure 5 is a vertical section taken on the line 5-5 of Figure 2.

Figure 6 is a horizontal section: taken on thev line 6-6 of Figure 2.

Figure 7 is a horizontal section similar to Figure 6 but with the mold in` open'position.

Figure 8 is a front elevation of the slide.

Figure 9 is a front elevation of the matrix holder.

Figure 10 is a partial sidev elevationl of the matrix plate.

Figure 11 is an enlarged-- transverse section through the mold.

Figure 12' isa detail ofthe operating leverV` for the'upper back-ing paper clamps;

Figure- 13 is' a detail view -of' the operating lever for theV lower backing-paper clamp.;

Figure 14 is a. detail view, partly invsection, showing the air cylinder and-controllpedal.

Figure15'is aisectio'ntaken on the line |5|5 of Figure 14. Y

Figure 16 isa diagrammatic representation of the cooling and-heating system'.-

In thevariousgures-like parts have been indicated by like reference numerals.

In the followingy description and'intlie claims, various details will bev identified by specific names for convenience; but they are intended to be as generic'in thelr'application as the art will permit.

Referring to the embodiment of the-invention shownx in the drawings,- the casting machine is illustrated as comprising a hollow pedestal 20 (Figure 1) which may comprise a base 2| f with upstandingrsides 22,A preferably cast integrally therewith; and having a cover'23/secured thereto, as'by bolts 24, to'provide'V anV airtightcham ber 25' adapted to constitute- J ancompressed air reservoir. A pressuregage 295` may be-lass'ociated therewith, if desired, to indicatethe air pressure Within said reservoir. The cover- 2'3 may have webs 26, 21 integrally cast therewith (Figures 1 landv 4)V to formy theY main support' for the mold or casting box 28'i The mold 28" comprises a backing member or slide 30 (Figures 4 8, l0) and a hinged matrix holder` 3|y comprisinga frame'32 and av matrix plate 33.

The slide 3|) may beA provided with lugs 34 (Figures 4 and 6)" which may be cast integrally therewith vand may slidably engage' guides 35 which are adjustably mounted on the webs 26, 21, as by bolts 36, extending preferably through enlarged holes'in said webs to permit transverse adjustment of said guides. Such adjustment ma;r be effected by means of adjusting bolts 31 bearing against said guides 35 andca-rriedinlugs 38 formedl on thev webs 26, 21.

The' frame^32"may'be hinged by arms 39 (Fig- Vures 2, 4 and 7) to a pin 40 which is'carried in ears 4| supported by thev web 21. Thel matrix plate 33 may be pivotally mounted, as by a pin 42, on an arm 43;' likewise-carried by the pin 4U.

The mold` is held in the closed position by means of a rod 44 pivoted, as by a pin 45, to ears 46 which may be carried by the web 26. The rod 44 engages a slot 52 (Figure 2) formed in the free end of the arm 43 and is secured by a split clamping nut 5|] having an operating handle 5|. The split clamping nut 50 may be locked in position onthe `threaded end. of therod 44 by a bolt 54. A flange 55 may be associated with the frame 32 and adapted to engage a positioning flange 56.carried by the web 26 to determine the posi- Vtion `of the matrix holder 3| when closed and to prevent the holder from exerting suiiicient pressure upon the slide 30 to interfere with the operation thereof.

The. frame 32V may carry an arm 51 (Figures 2, 4 vand 7) adapted to engage a latch 58 to lock the frame and matrix plate in open position. The latch -58 may bev pivoted to one of the ears 4| of the web 21, as by a pin 59, and may be held in cooperative position with respect to the arm 51 by'a'.Vv spring 60'. The latch 58 may be manually released when; the mold 28 is tobe: closed. The mold 28 is mounted at a slight inclination to the vertical, for example5, sothat the' molten metal flows down the slide 30, generally outof contact Withthe lmatrixzon the matrix holder 3|, vthereby protecting the matr'ixfrom injury or distortion due to:` contact with the stream of hot metal.

The slide 30 (Figures 5'8, andl 11) is formed with aplane surface 6| constituting the back of the mold. cavity,.and with a surface 62, offset with respect to the surface 6|,. andv connected thereto by a beveled.. surface 63' which is adapted to guide themetal to. the mold: cavity during the pouring operation'. Av cover plate 65 maybe secured to` a` bead 66 (Figures` 3, 5-7, and 11) formedonthe backV of the slide 30, as Vby bolts 61, to form..a chambery 1|) adapted to receive compressed air for the purpose to be described. A pluralityof transverse bores 1 are formed in the slide 30and extend/fromthe chamber 1|) to the surfaceV 6| of said slide.V Certain of said bores may be inclined to. the transverse axis of the machine'so that agreater separation is effected at the surface 6| than at the chamber 1|), thereby distributing the air from the chamber'10 over agre'ater: area ofsaid surface for thepurpose to be described.

The cover plate"65-also carries a lug 69adapted to receive'a shaft 12, whichmay'be secured by positioning nuts 13, and may be connectedto a suitable pistony 14 (Figures 4l and- 5), by which vertical movement of the. slide 30' is effected. The lug 69 may also be provided with a transverse port 15, communicatingl with the chamber 10, and adapted toreceive a pipe 116 through which compressed` air is supplied.

'I'he slide30'may be provided with a plurality of transverse bores 11 (Figures 5-8, 11) communieating with side channels closed by cover plates 8| held, for example, by screws 82. A coiled pipe 16 may be held in the bores `11 and channels 80 and may connect with flexible pipes 19, 84S (Figures 3, 4) through which a cooling fluid, such as water, maybe circulatedto maintain theslide atea desired 'castingtemperature Obviously, the pipe maybe cast directly into the slide or the slide may be cast around the formed pipe so as to obtain. an eflicient heat transfer relationship.

During the casting operation, the' slide 30 is adapted to be covered with backing paper 85, such' as a heavy calendered paper (Figures 5, 8 andA 11), For securing this paper in place, a pair -of upper clamps 86A and alower clamp 61 lil are provided. The clamps 86 are adapted to rest upon the surface 62 of the slide 30 an-d extend to a point adjacent the beveled surface 63 thereof. Said clamps 86 may be provided with hub portions 83 offset laterally to afford clearance for the backing paper 85, and keyed to a shaft (Figures 4, 8 and 12), which is carried in suitable supports 9| formed on the slide 30. For operating the clamps 86, a lever 92 is provided, having a handle 93, and is pivoted at one end, as at 94, to a link 95. The link is pivoted at 96 to a lug 91 formed as a part of the slide 30. An arm 98 is keyed to the shaft 90 and is pivoted, as at 99, to the lever 92. The arrangement is such that the lever 92 and the link 95 constitute a toggle joint which, in the position illustrated in full lines in Figure 12, holds the clamps 86 securely against the backing paper 85. When the lever 92 is moved to the position illustrated in dotted lines in Figure 12, the toggle is broken and pivotal movement of the arm 98 causes the shaft 90 to rotate and thereby to swing the clamps 86 away from the backing paper for releasing the same.

The lower clamp 81 is carried by a support |00 (Figures 5, 8 and 13) which is journaled be.- tween spaced bearing blocks |0| secured to the bottom of the slide 30 by bolts |02. The support |00 may have an arm |01 associated therewith and pivoted at |06 to an adjustable link |08, which, in turn, is pivoted at |09 to a lever ||0 having a handle ||2. The lever ||0 is pivoted at ||3 to ears ||4 carried by the slide 30. When the lever 0 is in vertical position, as illustrated in full lines in Figure 13, the lower clamp 81 is held securely against the backing paper 85 on the surface 5| of the slide 30, but when the lever ||0 is in the position shown in dotted lines in Figure 13, the link |08 is elevated, thereby swinging' the clamp 81 away from the surface 6| and releasing the backing paper 85 therefrom.

The frame 32 is provided with marginal side ilanges I6, a bottom flange |1, and a top ange ||8 (Figures 5-7, 9 and 11) adapted to form a liquid-tight seal with the surface 6I of the sli-de 30 or with the backing paper 85 which may be positioned thereon. The. bottom flange ||1 may have a recess ||9 to slidably receive the lower clamp 81 and to effect a seal therewith. The flanges ||6, ||1 and ||8 form the sides of the mold and dene the peripheral edges of the cast stereotype plate. The clamp 81 constitutes a plunger to apply pressure to the molten metal in themolcl cavity. The flange ||8 is spaced from the surface 62 to provide a passage |50 terminating in a flared opening |5| through which the molten metal may be poured when the slide is in its lower position. When the slide is raised, the surface 6| engages the flange ||8 to close said passage and conne the molten metal under the pressure applied by said clamp 81.

The frame 32 may be provided with knockout plungers |52 seated, for example, in transverse recesses |53 in said frame (Figures 5 and 9), and having racks |54 engaging a gear |55 which is carried on a shaft |56 (Figures 1 5) journaled in said frame and having an operating handle |51 keyed thereto. When the. plungers |52 are retracted, molten metal may enter the recesses |53 and form slugs which cause the solidified riser or gate between the iiange 8 and the surface 62 to adhere to the flange ||8 when the mold is opened. When the handle |51 is rotated, the knock-out plungers |52 push the slugs out of the recesses |53 and release the. solidied riser from the ange ||8.

The frame 32 may also be provided with a plurality of upper horizontal bores |2| adapted to receive electrical heating rods |03 of any standard type which may terminate in side channels |22, closed, if desired, by a cover plate |23. The frame 32 may also be provided with lower horizontal bores |24 adapted to receive similar heating rods |04, terminating in side channels |25 covered, if desired, by a cover plate |26.

The matrix plate 33 may comprise a front section |30 and a back section |3| having suitable grooves |32 formed therebetween to receive a coiled pipe |34 (Figures 2, 5, 6, 9 and 11), having terminals connected to flexible pipes |38, |39 through which a cooling fluid, such as water, may be circulated. The pipe |34 may be integrally formed or cast into the matrix plate 33 or the matrix plate 33 may be cast as a single section around the formed pipe |34, as desired.

Said matrix plate 33 may be provided with a pair of side clamps |40 secured to the edges thereof, as by screws 14|, extending through elongated slots |42 (Figures 10 and 11) formed in said side. clamps to permit transverse movement thereof with respect to the matrix plate. said clamps |40 may be provided with ilanges |43 which are adapted to seat in grooves |44 formed at the two side edges of the matrix plate for gripping the edges of the matrix. Spring fingers |46 may be formed at the bottom of the 33 when the mold is opened for removal of the f cast stereotype plate. When the mold is in closed position, the matrix is held against the flanges I6, |,1 and I8 of the frame 32 which extend entirely around the periphery of the matrix and securely clamp the marginal edges thereof.

The matrix plate 33 may be provided with a plurality of apertures |60 located in a row across the top thereof (Figures 5 and 9) and communieating with bores |6| terminating at the edges of said plate. The apertures |60 serve to release any air which may become entrapped at the back of the matrix |45 during the casting operation and to prevent the same from being compressed and interfering with the normal position ofthe matrix against the matrix plate.

Pivotal adjustment of the matrix plate 33 is obtained by means of bolts |62 (Figures 6 and 7), carried in said plate 33, and engaging adjustable bolts |63 carried on the arm 43, the adjustment being such as to permit a slight pivotal movement of the matrix plate about the pin 42, so that the plate may firmly seat against the flanges H6, H1 and ||B of the frame 32 when the mold is in closed position.

For operating the slide there is provided a housing |64 having acylinder |65 therein (Figures 1, 2, 5, 14 and 15) in which the piston 14 is seated. The housing |64 may be carried on the pedestal 29 and may be provided with a Vcap |66 through which the shaft 12 extends. The

cylinder |65'fcommunicates through a bore |61 with the air reservoir 25 and` is provided with a valve mechanism comprising a housing' |68 and a valve |69- adapted to seatthereon for controlling the flow of air from the reservoir'to the cylinder. The valve |89 maybe mounted on a stem |.10 and normally held in closed position by a spring |1|. For releasing the same, a foot lever |12 is provided having an abutment |13 adapted to bear against an adjustable bolt |14 carried by the stem |10.

The lever |12 may be formed with a hub |15 which may be pivoted, as by a pin |16, between ears |11 formed on` the housing |64. The lever |12'- is also provided with a shoulder |80 which is adapted to'engage. an'abutment |8| formed on the base 2| to limit the downward movement of the lever.

For locking the lever |12. in' its lower position, there is provided a link |82 having a shoulder |83 adapted to engage any abutment |84 formed on a plate |85 which may be secured to the housing |64 in any convenient manner. The link |82 may slidably engage a screw |86 and may be pivotally connected, as at |81, to one web |88 of a foot pedal |89, having a rear edge |90 and a front edge |9|. 'I'he foot pedal |89 is provided with apair of Webs |88, which extend on oppositesides of the lever |12.. and are'pivoted thereto, asI by a pin |93.

The arrangement is such that pressure on'the front edge |9| ofY the foot pedal |89- depresses vthe lever |12 and causesthe link |82 to lock against the abutment |84, as-illustrated in Figure 14, thereby opening. the valve |69 and holding the same in openy position. Pressure on the rear edge |90 of the pedal |89v causes' pivotal movement of the pedal about the pin |93, thereby withdrawing the link |82. from engagement with the abutment |84 and permitting the valve |69 to be closed by the action of the spring |1|.

'I'he cylinder |65 is closed at the top whereby upward movement of the piston compresses the air trapped within the upper part of the cylinder and forms a cushion to retard the movement of the piston and the associated mechanism.

A port |96 may be located in the housing-,|64 in a positionA to be uncovered when the piston hasneared the end of its normal operating stroke. This port |96 is connected, through a pressurereduction valve |91 and a gage |98, to the pipe 16 by which air is applied to the chamber 10 at the back of the slide 3.0.

rI-'he matrix plate 33 may be provided with a boss` |99 (Figures 2 and `6) having a Well 200 rearwardly inclined toreceive a thermometer 20| and with a well 202 adapted to receive the bulb 203 of a thermal-responsive device 204. A boss 205 may be formed onthe slide 30v (Figure 3) having wells 206, 201 to receive a thermometer 208 and the bulb 209'of a thermal-responsive device 2|0 respectively.

The thermal-responsive devices 204 and 2|0 may constitute make and break. relays operated by an expansible fluidvcontained in the bulbs 203 and 209 in response to temperature variations in the matrix plate 33 and in the slide 30 respectively. They may be supported on the apparatus in any convenient position and may be connected to a supply main 2|| (Figure 16) tocontrol the ,current to solenoid valves 2|2, 2|3 respectively exible-pipes 84 and |39'may be connected to a. discharge line 2|5. The thermal-responsive relays 204, 2|0 and the valves 2|2, 2|3. may be of any standard type adapted to admit cooling Water ata given maximum temperature and to interrupt the ilow of cooling Water at a given minimum temperature. A signal light 2|6 may be connected in parallel with the solenoid valve 2|2- so as to indicate when the temperature conditions of the matrix, plate are suchas to require cooling water, in which case the temperature is too high for pouring.

The valves 2|2, 2|3 may be supported by the pedestalf20. in any'convenient position. Suitable connections are. also made from main 2|| to the heating rods |03,. |04 so that these rods are energized Whenever the main switch (not sho-wn) is closed.

Inthe operation of this device, the backing paper 85, which preferably comprises a sheet of strong, calendered paper, is inserted under the clamps 86 and between the hub portions 83 thereof, and is extended downwardly under the lower clamp 81, the clamps 8.6 and 81 being released by suitable operation of the levers 92 and for this purpose. Thereafter, saidlevers are operated to cause the clamps 86 and 81 to engagethe backing paper and to. securely hold the same in position. The clamps 86 are adapted to cause the paper to bend over the inclined surface 63 ofthe slide 30 and are of such thickness that the face of: theclamps 86 and-the. face of the backing paper over the surface 6| lie in substantially the-same plane.

Ihe matrix is applied tothe matrix plate 33, preferably While at a high temperature, when the moldis open, as in Figure "I, and is temporarily held by the clamping strips |40. Thereafter, the frame 32 andlthematrix plate 33, with the.- lmatrix in position thereon, are swung into closed position. When the matrix plate 33 comes in contact withl the flanges ||6\ of. the frame, pressure is exerted which causes the clamps |40 to retract and to pull the edges of the matrix intoV the grooves. |4401 the matrix plate.` Thereaftenthe flanges H6', ||1A and ||8 of the frame 32 form a complete seal around the edges of the matrix andh'old the same under tension if any shrinkage tends to occur as in cooling.

'I'he frame 32y andy the matrix plate 33 are locked in closed position by means of the rod 44.and the lock nut 50', thev lock nut 50 being tightened by thehandle 5|. suciently to hold the flange 55 of the frame 32 firmly against. the stationary iiange56.

The slide 30, when properly positioned with respect to the frame 32 by means of suitable adjustment of the bolts 31, is locked in its position by tightening the bolts 36. This adjustment is such that the side and bottom flanges ||6 and .II-1 of the frame 32 effect a liquid-tight seal with the backing paper carried upon the slide 30 and with the clamp 81. The backing paper is preferably permitted to extend a substantial distance above the slide 30 so as to protect the top of the slide and the associated mechanism from the molten metal during the pouring operation.

With the parts thus assembled, the heating rods |03, |04 are energized to prevent the metal in the passage |50 and the metal around the clamp 81 from solidifying until the plate has been cast and the desired pressure applied thereto.

YThe cooling water is automatically supplied to the coils 18 and |34, if the temperature of the Cil slide and of the matrixplate exacts the predetermined value.

If, for example, a type metal is to be used having a pouring temperature of 550 F. and a freezing temperature of 475 F., the machine is preferably maintained at a temperature of about 120 F. The thermal-responsive devices 204, 2|@ may be adjusted to maintain the mold at about this selected temperature. If the machine is cold, as in the morning, one or more dummy plates may be cast to bring it up to the proper temperature. Thereafter, the temperature is controlled by the heating rods and by the cooling coils to maintain the desired casting conditions.

The molten metal is preferably maintainedat a predetermined temperature which is most suitable for pouring purposes, such,'for example, as a temperature of 550 F. as above mentioned. With the temperature of the metal before pouring and the temperature of vthe machine both constant, the plates are cast under uniform conditions and hence the cooling period, shrinkage, and other characteristics of the various vplates are substantially the same.

With the machine at the required temperature, the metal is poured into the flared opening |5| and passes downwardly over the surface 02 of the slide, is deflected by the inclined surface 03, and thence falls over the surface until the mold cavity gradually-becomes full of molten metal. It is to be noted that the backward inclination of the machine causes the metal toy flow downwardly over the backing plate instead of over the matrix, thereby preventing injury to the matrix impressions and preventing unequal heating or expansion of the matrix. As the metal gradually fills. the mold cavity, any air which is caught between the back of the matrix and the matrix plate 33 gradually rises to the top where it is released through the apertures |60, thereby permitting the matrix to lie at against the matrix plate.

The pouring is preferably continued until the molten metal fills the entire mold cavity and rises along the surface 52 to a point adjacent the flared opening Thereafter, the foot pedal |89 is depressed, opening the valve |69 and allowing air from the reservoir 25 to enter the cylinder |55 and raise the piston 14. This causes an upward movement of the slide during which the clamp 81 operates as a plunger, agitates the metal, and forces the same upwardly and out through the aperture between the inclined surface 63 of the slide and the top flange |8 of the frame 32. Continued movement of the slide 30 causes the surface 6| to register with the face of the flange llt and thereby substantially close the opening of the mold cavity. Thereafter, iurther movement of the slide compresses the molten metal within the mold cavity and causes the same to penetrate the impressions in the matrix.

This movement continues until the machine stalls, that is, until the pressure exerted by the molten metal balances the pressure applied to the piston 14. Furthermore, the sudden stoppage of movement of the slide 30, produced when the limit of compression of the molten metal is reached, produces an impact which greatly increases the pressure exerted upon the type metal.

The arrangement is such that, just before the piston 15 reaches the limit of its movement, the port |96 is uncovered and permits the air from the cylinder |35 to be applied through the pipe 16 and pressure-reduction valve |91 to the chamber and thence through the bores 1| to the back of the backing paper 85. This air pressure serves to force the backing paper away from the slide, exerting pressure on the back of the casting to hold the printing face firmly against the matrix as the metal shrinks While cooling. The pressure-reduction valve |91 reduces the air pres.- sure to a value such that the desired eiect is obtained. Obviously, this valve may be omitted if the air in the cylinder is at the proper pressure for the above purpose.

The heating rods |03 and |04 maintain the metal in molten position at the constricted points of the mold until the casting has been completed. Obviously, the clamp 81 and the passage |50 must b-e free if the proper operation is to be obtained. The cooling coils 18 and |34 remove heat from the mold at the large ilat surfaces of the casting, hasten solidication and prevent the mold from reaching too high a temperature due to continued casting operations. The controlled flow of cooling water in positive channels from the top to the bottom of the respective surfaces. ensures a uniform, controlled cooling effect.

Inasmuch as the matrix is firmly clamped around its periphery by the flanges H3, ||l and l |8, it is held under tension or in a stretched condition due to any shrinkage which may have taken place upon cooling from its original high temperature. The pressure which is maintained on the face of the matrix by means of the slide 30 and by the air applied to the backing paper 85 assists in holding the matrix flat against the matrix plate 33, whereby bulging or wrinkling, due to reheating by the hot metal, is prevented. Hence, the cast plate will correspond exactly in size and registration to the original impressions on the matrix.

If the pedal |89 is accidentally depressed when the mold is not lled with molten metal, the closed space at the top of the cylinder |65 acts as an air cushion to stop the piston and the slide Without injury to the apparatus.

When the metal has cooled below its solidicatio-n temperature and while it is still at an elevated temperature, such as 120 F., the cast stereotype plate is removed from the machine and furthercooling is effected in any convenient manner, using precautions to prevent buckling of the plate.

For removing the plate from the machine, the air pressure is released from the cylinder |85 by applying pressure to the rear edge |90 of the foot pedal |89, thereby withdrawing the link |82 from the abutment |84 and permitting the valve |59 to close. The Weight of the slide then causes the piston 14 to return gradually to its lower position as the air leaks around the edges of the piston. The lock nut 50 may then be loosened by suitable manipulation of the handle 5| to permit the rod M to be swung away from the arm 43, Whereupon the frame 32` and matrix plate 33 may be swung into the open position as illustrated in Figure '1. plate will adhere to the matrix and will accordingly be released from the backing paper and will follow the frame 32 and the matrix plate 33 as the same are swung into open position.

When the matrix plate 33 is separated from the frame 32, as by relative pivotal movement about the pin 50, the matrix will separate fro-m the cast stereotype plate and will be held by the clamps |40 against the matrix plate 33. The cast stereotype plate thereupon remains in the frame 32 and is held Within the flanges I6, ||1 and I8 thereof. 4rr'iove'd from this frameandm suitable manner.

'I'he gate between the flange f I8 Yand the sur- *The* plate may thenbeman'ually -rey be cooled in'any face1|i2lof the slide '30, may include lugs formed for Y further casting operations.

If desired, theipassage |50 may be designed so Yas to -providea thin strip of metal interconnect- `ing the cast stereotype plate and the gate. In such case, the plate hangs from the gate until torn away. This construction facilitates the re- Lmovalfof the plate from the-framei32, as` it preventsv therplate from dropping'until it is gripped and torn loose from the gate.

It is contemplated that the same backing paper may be usedfor several casting operations. `If further plates `a`re"tobe cast, the .machine may be'reclosed and the above operation repeated. It isrto be 4noted that the cooling coils maintain the -machine at the 'required temperature by removving the heat of casting. `C'onsequeritly, if the vvmoltenl'metal is always poured at a predetermined temperature, uniform results can be obtained.

` 'Although the above machine may be used with any type Iofmatrix;v it is particularly adapted for 4use 4with" themat'r'ix described'in my copendi-ng application Serial No.v 714,916, filed yMarch 10, 1934, forMatrix and method and apparatus for makingv the'same. vThe matrixl therein described is treated to obtain aA uniform back surface from Which all irregularities have been removed, for lexample, bygrinding the Isurface while the -matrx is still held ini position on thev type form. In this Way the matrix is so'formed that, when it-is placed 'on the smooth surface 'of the matrix 'pla-te, the Various impressions' retain their original'relative position and the stereotypeplate cast therefrom in the above-describedmarrneraccurately reproduces the original form from "whichfthe matrix was' impressed.

When used in thismannenthe stereotype plate is readyfformounting as soon asthe "backis planed to the desired thickness. The printing face is Aaccurate because y.the matrix is accurately formedl to eliminate vall irregularities therefrom, the matrixis" held against a flat surface inthe mold, the f matrix -is prevented from'bulging or distorting, theV plate-'is vheld in engagement :with the matrix'while cooling and solidifying, and the castingfoperation-is carried out-at predetermined temperatures. The process accordingly reduces the Lmanipulative steps-'toa minimum, renders manual correction ofthe plate unnecessary, yand produces a cast stereotypeplate at low cost having characteristics suitable 'for high 'quality printing.

It is to be vunderstood that the present invention is equallyapplicable 'to' the casting of I curved or flat stereotype plates. A machine v`for producing ilat plates has'been illustrated by way of example only `and not vas a limitation of= the invention. l

lAlthough a l particular embodiment of vthe lnvention has been shown and described for purposes-of illustration, itis to be understood that variousfchanges andmodications may bemade thereinby av person skilled in the art without dethe cast stereotype plate tolhold the plate in" pressure engagement with the matrix and 'to compensate for shrinkage.

--2.`'I'he process o'f casting stereotype 'plates which comprises applying an impact to the molten "metalto compress thesame, and to `causethe 3sarnevto'f penetrate the matrix impressions, maintaining 'the molten metal under pressure, and apply-ng pressureto the back of the cast plate adapted to compensate for shrinkage as the. plate cools.

`3. 'The/method of casting stereotypeA` plates in -a mold which comprises applying moltenmetal to 'themoldyclosing the mold and applying pres- 4sure tothe molten metal sucient to compress the 'metal and force the same into the matrix lmpressions andfwhile the plying 1"fluid pressure to the back surface of the cast' plate to hold the plate inV pressure engagement withthe'matrix and to compensate for shrinkage.

4. The method of casting stereotype plates in a mold which comprises maintaining themolten metal under `fluid pressure until solidication takes place 'so as to force the metaliinto the matrix limpressions and as the fluid'` pressuredimini'shesjdue to solidication, supplementingthe same by applying additional pressure to the back of the castA plate so as to` holdv theplate in pressure vengagement with the matrix untilthej'plate is completely solidified.

"5. method f vcasting stereotype plates in a. moldk whichcomp'rises placing a matrix containing `impressions. of the printing faces, andv aexliblelba'clringsheet on opposite supporting surfaces of 'a` mold to form a `mold cavity therebetween; pouring molten metal into said mold cavity, Aholding-saidmolten metal under uid presvsure toforce the same into the impressions in the matrix,Jv toremove air therefrom and to prevent buckling ofthe matrix, and as the metal solidies applying fluid pressure in back of saidI backing material and over substantially the entire area thereof tocausef'the backing `material' to apply pressureagainst substantially the entire vback of the cast plate-so as to compensate for shrinking of 'the' metaly while cooling and to maintain the plate inl-pressure engagement with Athe matrix throughout the casting operation.

^ GEORGEW.' BUNGAY.

metal is solidifying, apy 

